java: cache database table with 1 hour refresh

Question

I need some cache solution for java. I need to store content of 1 db table with 1 hour eviction then clear all values and populate data from table again.

I was looking into guava cache but it seems it does not provide required api in CacheLoader. Method CacheLoader.load populates only 1 value (so I want populate all values simultaneously) and CacheLoader.loadAll should be triggered by getAll call which is should be avoided in my case.

This is a pseudo code of what I want:

Cache<String, String> cache = CacheBuilder.newBuilder()
    .expireAfterWrite(1, TimeUnit.HOURS)
    .build(new CacheLoader<String, String> {
         public Map<String, String> loadAll()  {
             // some logic for retrieving data from db  
         }
    })

...
String value = cache.get(key)

Possible duplicate of this. But it seems pretty old and doesn't contain desired solution.

Also I have a different use cases, in some of them data should be retrieve from web server or file on file system so I don't want to rely on any database specific approach as hibernate cache or something of the kind.

Thanks!

Using JCache is better for Server environment. You can use Ignite Apache as an implementation. — LHA, Mar 15 '18 at 21:19
Apache Ignite is external data grid, isn't it? I mean I want something more easier to implement and deploy — Normal, Mar 15 '18 at 21:27
I simple need ConcurrentHashMap with eviction time support and listener on expiration — Normal, Mar 15 '18 at 21:29
JCache can work as local memory cache (Similar Guava Cache). Very easy to use. — LHA, Mar 16 '18 at 13:54

score 4 · Accepted Answer · answered Mar 15 '18 at 22:20

4

Have you looked at Guava's Suppliers with memoization? There's support for Supplier memoization with eviction. You can use it to build something like this:

public class DatabaseDataProvider {

 private final Supplier<Map<String, String>> dbDataSupplier;

 public DatabaseDataProvider(long duration) {
  final Supplier<Map<String, String>> supplier = () -> loadDbData();

  if (duration <= 0) {
   this.dbDataSupplier = supplier; //no caching
  } else {
   this.dbDataSupplier =
    Suppliers.memoizeWithExpiration(supplier, duration, TimeUnit.SECONDS);
  }

 }

 public Map<String, String> getAllDbData() {
  return dbDataSupplier.get();
 }

 private Map<String, String> loadDbData() {
  //DB magick
 }

answered Mar 15 '18 at 22:20

hovanessyan

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wow, looks like exactly what I want. Let me look into and examine the solution. – Normal Mar 15 '18 at 22:37
@hovanessyan is there a way to trigger guava cache update based on a table update in database? – OTUser Jun 04 '19 at 15:15
@RanPaul Yes, you can implement such a mechanism, but It depends on where the update comes from. If the update is coming from your codebase, you can fire an even after the update is committed and register listener for that event, that will intercept it and trigger the Guava logic. If it's also possible that the update be performed on DB level (e.g. someone manually executes an update statement) - the same logic applies as above - you need to fire an event and react based on it (see CDC pattern). – hovanessyan Jun 06 '19 at 17:35
@hovanessyan am looking for the second approach, when an update is performed on db cache needs to be refreshed, would you be able to answer my question https://stackoverflow.com/questions/56466572/trigger-guava-cache-refresh-when-a-table-is-updated?noredirect=1#comment99524715_56466572 – OTUser Jun 07 '19 at 14:36

java: cache database table with 1 hour refresh

1 Answers1